Speed adjustment for phonograph turntables



Dec. 4, 1951 c. B. DALE I SPEED ADJUSTMENT FOR PHONOGRAPH 'TURNTABLES Filed Jan. 3, 1951 INVENTOR. 0/422 ,5. Dad? BY Pate nted Dec. 4, 1951 Colin B. Dale, Oak Park, 111., assignor=to Webster-- Chicago Corporation, Chicago, 111., saicorpnration of Illinois Application, January 3, lesijiserial' No. 2043-67 7 Claims. (01. than This invention relates to a phonograph pitch control whereby a very fine adjustment may be obtained in the operating speed of its turntable and of the disc record which is rotated therewith. The rangeof speed adjustment is relatively small, perhaps only enough to cover a note or two in the musical -scale,'but ample for raising or lowering the pitch of the reproduced sounds which are given forth by the phonograph.

A primarypurpose served by the present adjustmentmearis is tobring the pitch of the reproduced sounds, particularly musical notes, into perfect-harmony with that of an accompanying instrument, so "that the two may be played together if desired. The invention is applicable to 'phonographs which have operating speeds for playing records of different diameters, the most common at the present being 33%, 45 and 78 r. p. m. In some respects the adjustment may be likened to that of a 'vernier control inasmuch as it operates within narrow limits to produce a very fine adjustment which is extremely accurate. I

A suggestive embodiment of this invention is illustrated in the accompany drawing wherein:

Figure l is a fragmentary plan viewof a phono graphequipped withth'e present pitch control, the turntable being "partly broken away to exhibit' a conventional three-speed drive mechanism'thereior;

"Fig.1'2 which isasimil'ar-view shows the base platform'of the turntable also broken away to exhibit in elevation the pitch control for the turntable;

Fig. 3 is a fragmentary perspective view showing the pitch control in connection with a turntable drive utilizing a single idler wheel intermediately of the drive shaft and friction wheel which drives the turntable; J I

Fig. 4 is a similar "view showing the drive-shaft in direct engagement with the friction wheel, thereby dispensing with any intermediate idler wheel in the transmission;

iormed with adepending marginal'flange l is mounted to rotate within a circular well, 8 tha is provided in the usual base B in the form of a platform which-carries on its top face a speed control handle S and also a pitch control handle P tor the adjustment that is special to this invention.

1 11c operating mechanism for the turntable may include the driving end portion of the shaft Ii} forming part of amotor M (see Fig. 5 which is journaled for rotation within spaced bearings ll and 12 wherein the shaft is later-ally supported; a plurality of stepped idle-r wheels l4, l5 and Hi having difierent diameters; and a frietion wheel [8. These several parts are accommodated below the platform B or within the space between the turntable andplatfor m, all of them being mounted torotate about vertical axes. The idler wheels are-carried upon a movable mount which is operable to position any selected idler between the shaft I 0 and friction wheel P8- to transmit "thereth rough motion at a desired speed from the power shaft to the triotion wheelwhich normally remains in engage-- ment with the flange l of the turntable. This form :of change speed drive is typical of several that may he employed in connection with the present invention; fact a single speed drive, with or without an intermediate idler wheel, may optionally'be used '(see Figs. 3-6).

The friction wheel 18 is provided with a bushing t9 constituting therefor a bearing that is journaled for rotation upon a post 20 which upstands from an arm -24 at a point near one end thereof; the opposite arm end is provided with a slot 2 2 extending longitudinally of the arm,

toreceive a pivot pin 23 which 'upstands from g .with the turntable flange (at the point a) and is itself' drivingly engaged (at the point 1)) by one of the several idler wheels 14, I5 and 1-6' comprised in the change speed drive of Figs. 1 and 2;, or by the single idler wheel 28 of Fig. '3, or directly-by the power shaft ill of Figs. 4-6-. The pull exerted by-this spring upon the mounting arm is in the direction requisite'for mam--- taining an effective pressure in the frictional drivlng engagement between the wheel I8 and the turntable flange I and also an effective pressure in the frictional driving engagement between the shaft III (or one of the idler wheels driven thereby) and the same wheel I8, thereby to assure a steady transmission of motion therethrough to the turntable. Normally the tension of this spring is light so as to minimize the lateral pressure between (1) the bearing of the turntable T,

and the mounting therefor, (2) the tread of the wheel I8 and the turntable flange, (3) the hearing IQ of the wheel I8 and the post 20 whereon it is journaled for rotation, (4.) the motor shaft I and its bearings II and I2, and the bearing of any idler which is interposed in the wheel train and the part thereof that is journaled for rotation. The direction of spring pull in relation to (1) the points of wheel engagement a and b, and (2) the sliding-pivotal mounting at 23 of the arm 2I', involves a toggle action in which but a slight tension on the part of the spring 25 produces an amplifiedpressure at the engagement points a and b.

As indicated in Fig. 3, the power end of the lever L is doubled back upon itself to a short upper ply 3I which is horizontally extended and apertured to receive the pivot pin it to stabilize the mounting for the lever. The upper ply 3| along one of its edges at the power end affords a convenient point for the application thereto of a variable power force which is transmitted from a cam 32 that is mounted fast on a rotatable pin 34 to which the pitch control handle P is also aifixed. The contour of this cam is shown to be that of a spiral so that in one extreme rotative position the power end of the lever is relatively close to the axis of the pin 34, whereas in the opposite extreme rotative position it is relatively remote therefrom; also the fulcrum point 26 for the lever L is shown as relatively close to its power end so that the movement of its weight end is amplified with the result that in one adjusted position the spring 25 exerts but a relatively light tension, whereas in its opposite adjusted position the spring exerts a relatively heavy tension such as to increase noticeably the friction which obtains between (1) the turntable T, (2) the friction wheel I8, (3) the motor shaft, and (4) the idlers (if any) comprised in the wheel train, and their respective rotatable mountings. In Fig. 6 an exaggerated showing is made of the direction and extent of movement of the friction wheel I8 and power shaft ID in response to braking of the drive mechanism in the manner already described. The cam control for operation of the lever, however, permits a very fine adjustment to be made, the lever being shiftable to any selected position within its range of movement and being there maintained due to the constant tension of the spring 25 which exerts its force reactively to hold the parts motionless through an indefinite period,

By the means described, I have provided what amounts to a Vernier speed adjustment which is effective through imposition of a variable frictional pressure at the bearings of the several parts comprised in the transmission of power to the turntable to control accurately although narrowly, the operating speed of the latter. Any slight change in such operating speed will, in consequence, raise or lower the pitch of the reproduced sounds emanating from the phonograph. In this way it is possible to bring the pitch into exact harmony with an accompanying piano or other instrument, thereby rendering the phonograph useful under conditions where otherwise its operation would be wholly unacceptable.

I claim:

I. In a phonograph turntable drive of the type which utilizes a driven wheel in frictional engagement with a marginal flange depending from the turntable, the friction wheel being carried on a mounting which is shiftable transversely of the axis of the turntable to vary the position of the friction wheel relative to its flange, the feature of improvement which comprises a lever of the first-class mounted to swing its Weight end toward and from the wheel axis, a tension spring interconnecting the weight end of the lever and the wheel mounting at a point adjacent the wheel axis, the lever at its power end being reversely bent to provide a doubledback portion, a post constituting a fulcrum for the lever traversing an aperture therein and also anaperture in the doubled-back portion of the lever, and a camin engagement with the lever at its power end for operation thereof, counter to tension of the spring, to a selected distant position relative to the wheel axis, thereby to determine the tension of the spring and of the force transmitted therethrough to the mounting transversely of the axis of wheel rotation.

2. In a phonograph turntable drive of the type which utilizes a driving wheel coacting frictionally with a driven wheel in frictional engagement with a marginal flange depending-from the turntable, together with an elongated rigid mounting whereon near one end thereof the driven wheel is journaled for rotation, the mounting near its opposite end being pivotally and slidably movable transversely of the axis of the turntable eccentrically thereof to simultaneously vary the position of the driven Wheel relative to both the. driving wheel and to the turntable flange, the feature of improvement which comprises a rigid lever disposed beyond the confines of the turn-. table and mounted to swing its weight end toward and from the driven wheel axis, a tension 15 spring interconnecting the said lever and the driven wheel mounting at a point adjacent the axis of the driven Wheel so disposed as to exert its pulling force on the mounting intermediately of the driving and driven Wheels, and a cam in engagement with the lever for operation thereof, counter to tension of the spring, to a selected distant position relative to the driven wheel axis, thereby to determine the tension of the spring and of the force transmitted therethrough to the mounting transversely of the axis of the driven wheel/ 3. In a phonograph turntable drive of the type which utilizes a driving wheel coacting frictionally with a driven wheel in frictional engagement with a marginal flange depending from the turntable, together with an elongated rigid mounting whereon near one end thereof the driven wheel is journaled for rotation, the mounting, near its opposite end being pivotally and slidably movable transversely of the axis of the turntable eccentrically thereof to simultaneously vary the position of the driven wheel relative to both the driving wheel and to the turntable flange, the feature of improvement which comprises a rigid lever disposed beyond the confines of the turntable and mounted to swing its weight end toward and from the driven wheel axis, a tension spring connecting the said lever end at a point relatively distant from the fulcrum with the driven wheel mounting at a point adjacent the axis of the driven wheel and so disposed as to exert its pulling force on the mounting intermediately of the driving and driven wheels, and a cam in engagement with the lever at a point relatively close to the fulcrum and operable to impart an amplified movement to the weight end of the lever, counter to tension of the spring, to a selected distant position relative to the driven wheel axis, thereby to determine the tension of the spring and of the force transmitted therethrough to the mounting transversely of the axis of the driven wheel.

4. In a phonograph turntable drive of the type which utilizes a driving wheel coacting frictionally with a driven wheel in frictional engagement with a marginal flange depending from the turntable, the driven wheel being carried on an elongated rigid mounting, near one end thereof, which is shiftable transversely of the axisof the turntable to simultaneously vary the position of the driven wheel relative to both the driving wheel and to the turntable flange, the feature of improvement which comprises a rigid lever of the first class disposed beyond the confines of the turntable and mounted upon a fulcrum to swing its weight end toward and from the driven wheel axis, a tension spring interconnecting the lever weight end and the wheel mounting at a point adjacent the axis of the driven wheel and so disposed as to exert its pulling force on the mounting intermediately of the driving and driven wheels and a'cam in engagement with the power end of the lever for operation thereof, counter to tension of the spring, to a selected distant position relative to the driven wheel axis, thereby to determine the tension of the spring and of the force transmitted therethrough to the mounting transversely of the axis of the driven wheel.

5. In phonograph turntable drive of the type which utilizes a driving wheel coacting frictionally witha driven wheel in frictional engagement with a marginal flange depending from the turntable, the driven wheel being carried on an elongated rigid mounting, near one end thereof, which is shiftable transversely of the axis of the turntable to simultaneously vary the position of the driven wheel relative to both the driving wheel and to the turntable flange, the feature of improvement which comprises :a rigid lever of the first class disposed beyond the confines of the turntable and mounted upon a fulcrum to swing its weight end toward and from the driven wheel axis, a tension spring connecting the lever weight end at a point relatively distant from the fulcrum with the wheel mounting at a point adjacent the driven wheel axis and so disposed as to exert its pulling force on the mounting intermediately of the driving and driven wheels, and a cam in engagement with the power end of the lever at a point relatively close to the fulcrum and operable to impart an amplified movement to the weight end of the lever, counter to tension of the spring, to a selected distant position relative to the driven wheel axis, thereby to determine the tension of the spring and of the force transmitted therethrough to the mounting transversely of the axis of the driven wheel.

6. In a phonograph turntable drive of the type which utilizes a driving wheel coacting fric tionally with a driven wheel in frictional engagement with a marginal flange depending from the turntable, the driven wheel being carried on an elongated rigid mounting,- near one end thereof, which is shiftable transversely of the axis of the turntable to simultaneously vary the position of the driven relative to both the driving wheel and to the turntable flange, the feature of improvement which comprises a rigid lever of the first class disposed beyond the confines of the turntable and mounted to swing its weight end toward and from the driven wheel axis, a tension spring interconnecting the Weight end of the lever and the wheel mounting at a point adjacent the driven wheel axis andso disposed as to exert its pulling force on the mounting intermediately of the driving and driven wheels, a pivotally mounted cam in engagement with the lever for operation thereof, and a pitch control handle connected fast with the cam for operation thereof, the cam, when operated, acting to swing the lever, counter to tension of the spring, to position its weight end at a selected distant point relative to the driven wheel axis, thereby to determine the tension-of the spring and of the force transmitted therethrough to the mounting transversely of the axis of the driven Whheel.

7. In a phonograph turntable drive of the type which utilities a driving wheel coacting frictionally with a driven wheel in frictional engagement with a marginal flange depending from the turntable, together with an elongated rigid mounting whereon near one end thereof the driven wheel is journaled for rotation, the mounting near its opposite end being pivotally and slidably movable transversely of the axis of the turntable eccentrioally thereof to vary the position of the driven wheel relative to both the driving wheel and to the turntable flange, the feature of improvement which comprises a rigid lever disposed beyond the confines of the turntable and mounted to swing its weight end toward and from the driven wheel axis, a tension spring interconnecting the said lever end and the wheel mounting at a point adjacent the axis of the driven wheel and so disposed as to exert its pulling force on the mounting intermediately of the driving and driven wheels, and a manually adjustable motion-transmitting means in engagement with the lever for operation thereof, counter to tension of the spring, to a selected distant position relative to the driven wheel axis, thereby to determine the tension of the spring and of the force transmitted therethrough to the mounting transversely of the axis of the driven wheel.

COLIN B. DALE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 405,978 Allen June 25, 1889 2,261,889 Schnieder Nov. 4, 1941 2,504,199 Johanns Apr. 18, 1950 

